JPWO2017057217A1 - Multilayer sheet for solar cell encapsulant, method for producing multilayer sheet for solar cell encapsulant, and solar cell module - Google Patents

Abstract

The multilayer sheet for solar cell encapsulant (10) of the present invention is used for encapsulating solar cell elements, and is a resin layer containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component. (A) and an adhesive layer (B) provided on one side or both sides of the resin layer (A). The adhesive layer (B) is at least selected from an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 920 kg / m 3 or less. A kind of ethylene copolymer (B2) (excluding the epoxy group-containing ethylene copolymer (B1)).

Description

  The present invention relates to a multilayer sheet for solar cell encapsulant, a method for producing a multilayer sheet for solar cell encapsulant, and a solar cell module.

With the recent increase in environmental problems, photovoltaic power generation is attracting attention as clean energy.
Photovoltaic power generation directly converts solar energy into electrical energy using a semiconductor (solar cell element) such as a silicon cell. The solar cell elements used here are thin and easy to break, and there are those whose functions deteriorate when directly in contact with the outside air. For this reason, the solar cell element is sandwiched between sealing materials to protect the solar cell element and prevent entry of foreign matter or moisture. Moreover, in order to provide sunlight to a solar cell element efficiently, the sealing material is required to be transparent.

  As a sealing material for solar cells, for example, a material containing an ethylene / vinyl acetate copolymer as a main component is widely used because it is excellent in transparency, adhesiveness, cost, and the like (for example, Patent Documents). 1-3).

JP 2002-190610 A JP 2010-53298 A JP 2011-140588 A

The level of technology required for various properties of solar cell encapsulants is increasing. The present inventors have found the following problems regarding a sealing material for solar cells containing an ethylene / vinyl acetate copolymer as a main component.
First, the sealing material for solar cells containing ethylene / vinyl acetate copolymer as a main component was inferior in moisture resistance. Therefore, depending on the type of transparent substrate or back sheet placed on the side where sunlight enters, the adhesion conditions, the usage environment of the solar cell, etc., moisture may enter the solar cell module, reducing the performance as a solar cell. There was a thing.
Solar cell encapsulant containing ethylene / vinyl acetate copolymer has lower volume resistivity than general polyolefin materials, and it has an insulating surface as a material to protect high power and high performance solar cells. May be insufficient.

Thus, the present inventors have found that conventional solar cell sealing materials as described in Patent Documents 1 to 3 are still insufficient in moisture resistance and insulation.
Further, according to the study by the present inventors, when the content of vinyl acetate in the ethylene / vinyl acetate copolymer is reduced, the moisture permeability of the solar cell encapsulant containing the ethylene / vinyl acetate copolymer decreases. It became clear that the moisture resistance was lowered and the volume resistivity was increased and the insulation was improved while the transparency and adhesiveness were deteriorated.
That is, it has been clarified that there is a trade-off relationship between transparency and adhesiveness, moisture resistance and insulation, and that the trade-off relationship cannot be improved by improving the polymer composition. That is, the present inventors have found that there is room for improvement in the viewpoint of improving the transparency, adhesiveness, moisture resistance, and insulation in a balanced manner in the conventional solar cell sealing material.

  This invention is made | formed in view of the said situation, and provides the multilayer sheet for solar cell sealing materials excellent in the performance balance of transparency, adhesiveness, moisture resistance, and insulation.

  The inventors of the present invention have made extensive studies in order to achieve the above problems. As a result, the above trade-off can be achieved by laminating a resin layer containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component and an adhesive layer containing a specific ethylene copolymer. It has been found that the relationship can be improved and the transparency and adhesiveness, and the moisture resistance and insulation can be improved in a balanced manner, and the present invention has been achieved.

  That is, according to this invention, the manufacturing method and solar cell module of the multilayer sheet for solar cell sealing materials shown below, the multilayer sheet for solar cell sealing materials are provided.

[1]
A solar cell comprising: a resin layer (A) containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component; and an adhesive layer (B) provided on one or both sides of the resin layer (A). A multilayer sheet for sealing material,
The adhesive layer (B) is at least selected from an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less. A multilayer sheet for a solar cell encapsulating material, comprising a type of ethylene copolymer (B2) (excluding the epoxy group-containing ethylene copolymer (B1)).
[2]
In the multilayer sheet for solar cell encapsulant described in [1] above,
The multilayer sheet for solar cell sealing materials in which the said contact bonding layer (B) was provided in both surfaces of the said resin layer (A).
[3]
In the multilayer sheet for solar cell encapsulant described in [1] or [2] above,
The multilayer sheet for solar cell sealing materials whose whole thickness is 50 micrometers or more and 2000 micrometers or less.
[4]
In the multilayer sheet for solar cell encapsulant according to any one of [1] to [3] above,
The multilayer sheet for solar cell sealing materials whose Haze measured based on JISK7136 is 40% or less.
[5]
In the multilayer sheet for solar cell encapsulant according to any one of [1] to [4] above,
The epoxy group-containing ethylene copolymer (B1) is composed of ethylene / (meth) acrylic acid glycidyl copolymer, ethylene / (meth) acrylic acid glycidyl / vinyl acetate copolymer, and ethylene / (meth) acrylic acid glycidyl / The multilayer sheet for solar cell sealing materials containing at least 1 type selected from a (meth) acrylic acid ester copolymer.
[6]
In the multilayer sheet for solar cell encapsulating material according to any one of [1] to [5] above,
The ethylene / polar monomer copolymer contains at least one selected from an ethylene / vinyl ester copolymer, an ethylene / unsaturated carboxylic acid ester copolymer, and an ethylene / unsaturated carboxylic acid copolymer. Multi-layer sheet for materials.
[7]
In the multilayer sheet for solar cell encapsulant according to any one of [1] to [6] above,
Solar cell sealing material in which at least a part of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) in the adhesive layer (B) is graft-modified with a silane coupling agent Multilayer sheet.
[8]
In the multilayer sheet for a solar cell sealing material according to any one of [1] to [7] above,
The content of the ethylene copolymer (B2) contained in the adhesive layer (B) is 100% by mass of the total amount of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). As a multilayer sheet for a solar cell encapsulant, which is 50% by mass or more and 99% by mass or less.
[9]
In the multilayer sheet for solar cell encapsulant according to any one of [1] to [8] above,
The resin layer (A) is a multilayer sheet for a solar cell encapsulant containing the ionomer of the ethylene / unsaturated carboxylic acid copolymer as a main component.
[10]
In the multilayer sheet for a solar cell sealing material according to any one of [1] to [9] above,
The multilayer sheet for solar cell sealing materials used in order to adhere | attach the electrically insulating resin film layer in which at least one surface is not corona-treated.
[11]
A production method for producing the multilayer sheet for a solar cell encapsulant according to any one of [1] to [10],
Resin composition (A) containing ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component, epoxy group-containing ethylene copolymer (B1), ethylene / polar monomer copolymer and density of 920 kg / Resin composition containing at least one ethylene copolymer (B2) selected from ethylene / α-olefin copolymers of m ³ or less (excluding the above epoxy group-containing ethylene copolymer (B1)) The manufacturing method of the multilayer sheet for solar cell sealing materials including the process of carrying out multilayer extrusion molding of the thing (B).
[12]
A substrate on which sunlight is incident;
A solar cell element;
A backsheet,
A sealing resin constituted by the multilayer sheet for solar cell sealing material according to any one of [1] to [10], for sealing the solar cell element between the substrate and the back sheet. Layers,
A solar cell module comprising:

ADVANTAGE OF THE INVENTION According to this invention, the multilayer sheet for solar cell sealing materials excellent in the performance balance of transparency, adhesiveness, moisture resistance, and insulation can be provided.
The multilayer sheet can also be used as an interlayer film for laminated glass, and can provide an interlayer film for laminated glass and a laminated glass excellent in the performance balance of transparency, adhesiveness, and moisture resistance.

  The above-described object and other objects, features, and advantages will become more apparent from the preferred embodiments described below and the accompanying drawings.

It is sectional drawing which showed typically an example of the structure of the multilayer sheet for solar cell sealing materials of embodiment which concerns on this invention. It is sectional drawing which showed typically an example of the structure of the solar cell module of embodiment which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, “X to Y” in the numerical range represents X or more and Y or less unless otherwise specified. Moreover, (meth) acryl means one or both of acryl and methacryl.

1. About the multilayer sheet for solar cell sealing materials FIG. 1: is sectional drawing which showed typically an example of the structure of the multilayer sheet 10 for solar cell sealing materials of embodiment which concerns on this invention.
The solar cell encapsulant multilayer sheet 10 (hereinafter also referred to as a multilayer sheet) according to the present embodiment is used for encapsulating a solar cell element, and is an ethylene / unsaturated carboxylic acid copolymer or its The resin layer (A) which contains an ionomer as a main component, and the contact bonding layer (B) provided in the single side | surface or both surfaces of the resin layer (A) are provided. A form in which layers other than the resin layer (A) and the adhesive layer (B) are included, for example, between the resin layer (A) and the adhesive layer (B) is also an embodiment of the present invention, but the resin layer (A) and A form in which the adhesive layer (B) is in direct contact is preferable.
The adhesive layer (B) is selected from an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less. And at least one ethylene copolymer (B2) (excluding the epoxy group-containing ethylene copolymer (B1)).

  According to the multilayer sheet 10 for a solar cell encapsulant according to this embodiment, an ethylene / vinyl acetate copolymer that has been conventionally used is provided by including a resin layer (A) and an adhesive layer (B). Compared with the solar cell encapsulant sheet containing, the transparency, adhesiveness, moisture resistance and insulation can be improved in a balanced manner. In particular, since it is excellent in moisture resistance and adhesion, it is excellent in moisture resistance adhesion and long-term stability of adhesion. Moreover, according to the multilayer sheet 10 for solar cell sealing materials which concerns on this embodiment, the adhesiveness outstanding also with respect to the surface which is not corona-treated of electrically insulating resin film layers, such as a polyester film, is shown.

In the resin layer (A), the ethylene / unsaturated carboxylic acid copolymer or a layer containing the ionomer as a main component is preferably composed of a single layer. Or a ratio of other copolymerizable monomers contained in the ethylene / unsaturated carboxylic acid copolymer may be composed of a plurality of layers.
The “main component” means that the ethylene / unsaturated carboxylic acid copolymer or its ionomer is contained in the resin layer (A) in an amount of 60% by mass or more.

The adhesive layer (B) is laminated on one side or both sides of the resin layer (A). The adhesive layer (B) is preferably provided on both surfaces of the resin layer (A) from the viewpoint of improving the adhesion between the multilayer sheet, the solar cell element, the transparent substrate, and the back sheet in a balanced manner.
Moreover, although it is preferable that the adhesive layer (B) is also composed of a single layer like the resin layer (A), it may be composed of a plurality of layers having different compositions and blending amounts of the copolymer. Good.

  The solar cell encapsulant multilayer sheet 10 according to the present embodiment has a plurality of layers formed by the resin layer (A) and the adhesive layer (B), more preferably the resin layer (A) and the adhesive layer. It is a two-layer sheet including (B), particularly preferably a three-layer sheet including an intermediate layer composed of a resin layer (A) and an outer layer composed of an adhesive layer (B) provided on both surfaces thereof.

In the present embodiment, the total thickness of the solar cell encapsulant multilayer sheet 10 is preferably in the range of 50 μm to 2000 μm, more preferably 50 μm to 1000 μm, and particularly preferably 50 μm to 800 μm. When the total thickness of the solar cell encapsulant multilayer sheet 10 is equal to or greater than the lower limit, damage to the solar cell element due to impact or the like can be further suppressed. Moreover, the transparency of a sheet | seat improves more as the whole thickness of the multilayer sheet 10 for solar cell sealing materials is below the said upper limit, solar light reception amount can be maintained, and output can be maintained much higher. Can do.
In addition, since the multilayer sheet according to this embodiment is excellent in the performance balance of transparency, adhesiveness, moisture resistance, and insulation, the entire thickness of the multilayer sheet can be reduced to 800 μm or less.

In the case of a two-layer sheet including a resin layer (A) and an adhesive layer (B), the thickness (a) of the resin layer (A) constituting the multilayer sheet according to this embodiment and the thickness of the adhesive layer (B) ( The ratio (a / b) to b) is 1/1 to 10/1, preferably 2/1 to 6/1. When a / b is within the above range, the performance balance of transparency, adhesion, moisture resistance, insulation, flexibility, heat resistance, and workability can be further improved.
Further, in the case of a three-layer sheet including an intermediate layer composed of a resin layer (A) and an outer layer composed of an adhesive layer (B) provided on both surfaces thereof, the resin layer (A The ratio (a / b) between the thickness (a) of one layer and the thickness (b) of the adhesive layer (B) is 1/1 to 10/1, preferably 2/1 to 6/1. is there. When a / b is within the above range, the performance balance of transparency, adhesion, moisture resistance, insulation, flexibility, heat resistance, and workability can be further improved. As long as the outer layer has the above thickness ratio, the thicknesses of the two outer layers may be different.

  In the multilayer sheet 10 for a solar cell encapsulant in the present embodiment, the flexural modulus measured according to JIS K7171 is preferably 50 MPa or more and 500 MPa or less, and more preferably 100 MPa or more and 450 MPa or less. When the bending elastic modulus satisfies the above range, the performance of the solar cell encapsulant multilayer sheet 10 such as fracture strength, impact resistance and puncture resistance and the productivity balance of the solar cell module may be further improved. it can. In order to achieve such a flexural modulus, the composition of the resin layer (A), the composition of the adhesive layer (B), the thickness ratio between the resin layer (A) and the adhesive layer (B), etc. can be adjusted as appropriate. Good.

In the multilayer sheet 10 for a solar cell encapsulant according to this embodiment, the moisture permeability measured under conditions of a temperature of 40 ° C. and a humidity of 90% RH is 15 g / (m ² · 24 h) or less in accordance with JIS Z0208. It is preferably 10 g / (m ² · 24 h) or less, more preferably 5 g / (m ² · 24 h) or less.
Since the multilayer sheet 10 for solar cell sealing materials whose moisture permeability is below the said upper limit is hard to hold | maintain a water | moisture content inside, it can suppress corrosion of a solar cell element or an electrode. As a result, the long-term stability of the solar cell module can be further improved.

In the multilayer sheet 10 for a solar cell encapsulant according to this embodiment, the Haze measured according to JIS K7136 is preferably 40% or less, more preferably 35% or less, and 30% or less. It is particularly preferred.
Thereby, the photovoltaic power generation amount of the solar cell module obtained can be further improved.

<Resin layer (A)>
The resin layer (A) contains an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component.

In the ethylene / unsaturated carboxylic acid copolymer or its ionomer, the structural unit derived from ethylene is preferably 65% by mass to 95% by mass, more preferably 75% by mass to 92% by mass. The structural unit derived from the acid is preferably 5% by mass or more and 25% by mass or less, more preferably 8% by mass or more and 25% by mass or less.
When the structural unit derived from ethylene is at least the above lower limit value, the heat resistance, mechanical strength, and the like of the multilayer sheet can be improved. Further, when the structural unit derived from ethylene is not more than the above upper limit value, the transparency, flexibility, adhesiveness and the like of the multilayer sheet can be further improved.
When the structural unit derived from the unsaturated carboxylic acid is at least the above lower limit, the transparency, flexibility, adhesiveness and the like of the multilayer sheet can be made better. Moreover, the workability of a multilayer sheet can be made more favorable as the structural unit guide | induced from unsaturated carboxylic acid is below the said upper limit.

Examples of the unsaturated carboxylic acid in the ethylene / unsaturated carboxylic acid copolymer include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, and monoethyl maleate. Etc. Among these, at least one selected from acrylic acid and methacrylic acid is preferable from the viewpoints of productivity and hygiene of the ethylene / unsaturated carboxylic acid copolymer.
In addition, these unsaturated carboxylic acids may be used individually by 1 type, and may be used in combination of 2 or more type.

  The ethylene / unsaturated carboxylic acid copolymer is preferably 0% by mass or more and 30% by mass or less, more preferably 0% by mass or more and 25% by mass with respect to 100% by mass in total of ethylene and unsaturated carboxylic acid copolymer. % Or less of other structural units derived from other copolymerizable monomers may be contained. Other copolymerizable monomers include unsaturated esters such as vinyl esters such as vinyl acetate and vinyl propionate; methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic. Examples include (meth) acrylic acid esters such as n-butyl acid and 2-ethylhexyl (meth) acrylate. When the structural unit derived from the other copolymerizable monomer is contained in the above range, it is preferable in that the flexibility of the multilayer sheet is improved.

In this embodiment, the ionomer can be used instead of the ethylene / unsaturated carboxylic acid copolymer. When the resin layer (A) contains an ionomer of an ethylene / unsaturated carboxylic acid copolymer as a main component, the moisture permeability of the multilayer sheet 10 for a solar cell encapsulant is reduced and the moisture resistance is further improved. It can be.
Examples of the ion source in the ionomer include alkali metals such as lithium and sodium; polyvalent metals such as calcium, magnesium, zinc and aluminum.

  As the ionomer, those having a neutralization degree of usually 80% or less are used. When the degree of neutralization is in the above range, a multilayer sheet excellent in transparency and storage stability at high temperatures can be obtained. Generally, it is preferable to use a solar cell encapsulant sheet having a neutralization degree of 60% or less, particularly 40% or less, from the viewpoint of transparency, adhesiveness and workability. Although the minimum of a neutralization degree is not specifically limited, For example, it is 1% or more, and 5% or more is preferable.

  The ethylene / unsaturated carboxylic acid copolymer can be obtained by radical copolymerization of each polymerization component under high temperature and high pressure. The ionomer can be obtained by reacting such a copolymer with a metal compound.

  The ethylene / unsaturated carboxylic acid copolymer or its ionomer has a melt flow rate at 190 ° C. under a load of 2160 g (JIS K7210-1999) of 0.1 to 150 g / 10 min in consideration of processability and mechanical strength. In particular, it is preferable to use a 0.1 to 50 g / 10 min.

  The resin layer (A) constituting the multilayer sheet according to the present embodiment contains an ethylene / unsaturated carboxylic acid copolymer or its ionomer in an amount of usually 80% by mass or more, preferably 90% by mass or more. When the ethylene / unsaturated carboxylic acid copolymer or its ionomer is contained in the above range, the transparency, insulation and moisture resistance of the multilayer sheet can be further improved.

  The resin layer (A) can contain various additives within a range that does not impair the object of the present invention. Examples of such additives include a crosslinking agent, a crosslinking aid, a silane coupling agent, an ultraviolet absorber, a light stabilizer, and an antioxidant.

As the cross-linking agent, an organic peroxide having a decomposition temperature of half-life of 1 hour is usually 90 to 180 ° C, preferably 100 to 150 ° C. Examples of such organic peroxides include t-butyl peroxyisopropyl carbonate, t-butyl peroxyacetate, t-butyl peroxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-bis. (T-butylperoxy) hexane, di-t-butylperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, 1,1-bis (t-butylperoxy) ) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, t-butyl hydroper Oxide, p-menthane hydroperoxide, benzoyl peroxide, p-chloro Benzoyl peroxide, t- butyl peroxy isobutyrate, hydroxyheptyl peroxide, di-cyclohexanone peroxide.
The crosslinking agent can be contained in an amount of usually 0.1 to 5 parts by mass, preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the ethylene / unsaturated carboxylic acid copolymer or its ionomer.

Examples of the crosslinking aid include polyunsaturated compounds such as polyallyl compounds and poly (meth) acryloxy compounds. Among them, polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate; poly (meth) acryloxy such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate Compound; and divinylbenzene.
The crosslinking aid can be contained in an amount of usually 5 parts by mass or less, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the ethylene / unsaturated carboxylic acid copolymer or its ionomer.

Examples of the silane coupling agent include a silane coupling agent having a vinyl group, an amino group or an epoxy group and a hydrolyzable group such as an alkoxy group. Among them, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, 3-glycidoxy Propylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N-2- (aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldiethoxysilane, 3 -Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane and the like.
The silane coupling agent can be contained in an amount of usually 5 parts by mass or less, preferably 0.02 to 3 parts by mass with respect to 100 parts by mass of the ethylene / unsaturated carboxylic acid copolymer or its ionomer. When the silane coupling agent is contained in the above range, the adhesion between the multilayer sheet and the protective material or solar cell element can be further improved.

  Moreover, in order to prevent deterioration of the multilayer sheet based on ultraviolet rays, it is preferable to contain an ultraviolet absorber, a light stabilizer, an antioxidant and the like in the resin layer (A).

  Examples of the ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2-carboxybenzophenone, 2-hydroxy-4-n- Benzophenone UV absorbers such as octoxybenzophenone; 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol, 2- (2′-hydroxy-3 ′, 5′-di benzotriazole ultraviolet absorbers such as t-butylphenyl) benzotriazole, 2- (2′-hydroxy-5-methylphenyl) benzotriazole, 2- (2′-hydroxy-5-t-octylphenyl) benzotriazole; Salicylic acid ester such as phenyl salicylate and p-octylphenyl salicylate Le-based ultraviolet absorber and the like are used.

As the light stabilizer, a hindered amine light stabilizer or the like is used.
As the antioxidant, various hindered phenol antioxidants, phosphite antioxidants, and the like are used.
The antioxidant, light stabilizer and ultraviolet absorber are each usually 5 parts by mass or less, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the ethylene / unsaturated carboxylic acid copolymer or its ionomer. It can be included.

Moreover, in addition to the additive mentioned above, additives, such as a coloring agent, a light-diffusion agent, and a flame retardant, can be contained in the resin layer (A) as needed.
Examples of the colorant include pigments, inorganic compounds, dyes, and the like, and examples of the white colorant include titanium oxide, zinc oxide, and calcium carbonate. When a multilayer sheet containing these additives is used as a sealing material on the light receiving side of a solar cell element, transparency may be impaired, but when used as a sealing material on the surface opposite to the light receiving side of the solar cell element Is preferably used.

  Examples of the light diffusing agent include inorganic beads such as glass beads, silica beads, silicon alkoxide beads, and hollow glass beads. Examples of the organic spherical material include acrylic and vinylbenzene plastic beads.

  Examples of the flame retardant include halogen flame retardants such as bromide, phosphorus flame retardants, silicone flame retardants, metal hydrates such as magnesium hydroxide and aluminum hydroxide, and the like.

<Adhesive layer (B)>
The adhesive layer (B) is at least one selected from an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less. Ethylene copolymer (B2) (excluding the epoxy group-containing ethylene copolymer (B1)).

Examples of the epoxy group-containing ethylene copolymer (B1) include a glycidyl group-containing ethylene copolymer.
Examples of the glycidyl group-containing ethylene copolymer include ethylene / (meth) acrylic acid glycidyl copolymer, ethylene / (meth) acrylic acid glycidyl / vinyl acetate copolymer, and ethylene / (meth) acrylic acid glycidyl / Examples thereof include at least one selected from (meth) acrylic acid ester copolymers.

The epoxy group-containing ethylene copolymer (B1) is composed of a polymerizable group such as glycidyl (meth) acrylate, vinyl glycidyl ether, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl methacrylate, and epoxy. It is obtained by copolymerizing a monomer having a group with ethylene. Further, an epoxy group may be introduced by graft polymerization of a monomer having an epoxy group to an ethylene-based copolymer.
The content ratio of the structural unit derived from the monomer such as glycidyl (meth) acrylate in the epoxy group-containing ethylene copolymer (B1) is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more. 25% by mass or less.
When the content ratio of the structural unit derived from the monomer such as (meth) glycidyl acrylate is equal to or higher than the lower limit, the multilayer sheet 10 for solar cell encapsulant and the solar cell module component (solar cell element, substrate, etc.) When the adhesive property of the solar cell sealing material is lower than the above upper limit, the processability as the multilayer sheet for sealing material is improved, and in addition, the transparency and flexibility of the multilayer sheet 10 for solar cell sealing material are also improved. Become better.
“Glycidyl (meth) acrylate” represents one or both of glycidyl methacrylate and glycidyl acrylate.

The “ethylene copolymer” in the epoxy group-containing ethylene copolymer (B1) means that a structural unit derived from ethylene is a main component. Furthermore, the “main component” here means that the content of “structural unit derived from ethylene” is the largest among all the structural units. For example, in the case of a copolymer composed of structural units derived from ethylene, glycidyl (meth) acrylate, and vinyl acetate, the ratio of the structural units derived from ethylene is the structural unit derived from glycidyl (meth) acrylate. Or larger than a structural unit derived from vinyl acetate.
The proportion of the “ethylene-derived structural unit” in the epoxy group-containing ethylene copolymer (B1) is preferably 50% by mass or more, more preferably 65% by mass or more, further preferably 70% by mass or more, and particularly preferably. 80% by mass or more. At this time, the epoxy group-containing ethylene-based copolymer can further include other monomer units other than the monomer having ethylene and a polymerizable group and an epoxy group.
Other monomers include vinyl esters such as vinyl acetate and vinyl propionate; acrylic esters, methacrylic esters, ethacrylic esters, crotonic esters, fumaric esters, maleic esters, maleic anhydride esters, itaconic esters, And unsaturated carboxylic acid esters such as itaconic anhydride. Examples of the ester group include alkyl ester groups having 1 to 12 carbon atoms, and more specifically, methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester, isobutyl ester, secondary butyl ester. And alkyl ester groups such as 2-ethylhexyl ester and isooctyl ester.
Among these, at least one selected from vinyl acetate and (meth) acrylic acid esters is preferable.

Specifically, in addition to a copolymer containing a structural unit derived from ethylene and a structural unit derived from glycidyl (meth) acrylate, in addition to these two structural units, a composition derived from vinyl acetate. Examples thereof include a copolymer containing at least one of a unit and a structural unit derived from a (meth) acrylic acid ester.
The content ratio of the structural unit derived from vinyl ester such as vinyl acetate and the structural unit derived from unsaturated carboxylic acid ester such as (meth) acrylic acid ester is preferably 30% by mass or less, and 20% by mass or less. It is more preferable. Thereby, the moisture permeability of the multilayer sheet 10 for solar cell sealing materials falls, and it can make moisture-proof further better.

  The lower limit of the content ratio of the structural unit derived from a vinyl ester such as vinyl acetate and the structural unit derived from an unsaturated carboxylic acid ester such as (meth) acrylic acid ester is not particularly limited, but is preferably 0.1 mass. % Or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more. Furthermore, the content ratio of the structural unit derived from vinyl ester such as vinyl acetate or the structural unit derived from unsaturated carboxylic acid ester such as (meth) acrylic acid ester is preferably in the range of 0.1 to 30% by mass, Furthermore, the range of 0.5-20 mass% is preferable, and the range of 1-20 mass% is especially preferable.

  The epoxy group-containing ethylene copolymer (B1) can be used singly or in combination of two or more different copolymerization ratios.

The ethylene-based copolymer (B2) contains at least one selected from an ethylene / polar monomer copolymer and an ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less.

  The “ethylene copolymer” in the ethylene copolymer (B2) means that a structural unit derived from ethylene is a main component. Further, the “main component” here means that the proportion of “ethylene-derived structural units” with respect to all the structural units is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 65% by mass. % Or more, particularly preferably 70% by mass or more.

  Examples of ethylene / polar monomer copolymers include ethylene / vinyl acetate copolymers, ethylene / vinyl propionate copolymers, ethylene / vinyl butyrate copolymers, and ethylene / vinyl ester copolymers such as ethylene / vinyl stearate copolymers. One kind or two or more kinds selected from a polymer, an ethylene / unsaturated carboxylic acid ester copolymer, an ethylene / unsaturated carboxylic acid copolymer, and the like can be used.

Here, the ethylene / unsaturated carboxylic acid ester copolymer is a polymer obtained by copolymerizing ethylene and at least one unsaturated carboxylic acid ester.
Specifically, a copolymer containing ethylene and an alkyl ester of an unsaturated carboxylic acid can be exemplified.
Examples of the unsaturated carboxylic acid in the unsaturated carboxylic acid ester include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride and the like.
Examples of the alkyl moiety in the alkyl ester of the unsaturated carboxylic acid include those having 1 to 12 carbon atoms, more specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl. And alkyl groups such as 2-ethylhexyl and isooctyl. In this embodiment, as for carbon number of the alkyl site | part of an alkyl ester, 1-8 are preferable.
In the present embodiment, a particularly preferred ethylene / unsaturated carboxylic acid ester copolymer is an ethylene / (meth) acrylic acid ester copolymer. Examples of such copolymers include ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / normal butyl acrylate copolymer, ethylene / isobutyl acrylate copolymer, ethylene / They are methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / normal butyl methacrylate copolymer, and ethylene / isobutyl methacrylate copolymer.

The ethylene / unsaturated carboxylic acid copolymer is a polymer obtained by copolymerizing ethylene and at least one unsaturated carboxylic acid. The unsaturated carboxylic acid ester may be copolymerized.
Specifically, a copolymer containing ethylene and an unsaturated carboxylic acid can be exemplified.
Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride and the like.
In the present embodiment, a particularly preferred ethylene / unsaturated carboxylic acid copolymer is an ethylene / (meth) acrylic acid copolymer.

  Among the above, ethylene / polar monomer copolymers are ethylene / vinyl acetate copolymer, ethylene / (meth) methyl acrylate copolymer, ethylene / (meth) ethyl acrylate copolymer, ethylene / (meth). At least one selected from propyl acrylate copolymer, ethylene / (meth) butyl acrylate copolymer, and ethylene / (meth) acrylic acid copolymer is particularly preferably used. In the present embodiment, the above-described resins may be used alone or blended.

The content of the polar monomer in the ethylene / polar monomer copolymer is preferably 5% by mass or more and 40% by mass or less, more preferably 8% by mass or more and 35% by mass or less, and particularly preferably 8% by mass or more. 30% by mass or less.
When the content of the polar monomer is within this range, the balance of adhesion, transparency, mechanical properties, and film formability of the solar cell encapsulant multilayer sheet 10 can be further improved. The vinyl acetate content can be measured according to, for example, JIS K7192: 1999.

  The production method of the ethylene / polar monomer copolymer is not particularly limited, and can be produced by a known method. For example, it can be produced by a conventionally known high pressure autoclave method or tubular method. A commercially available ethylene / polar monomer copolymer may be used.

As the ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less in the ethylene copolymer (B2), the content of all structural units (monomer units) constituting the copolymer is 100 mol. %, The content ratio of the structural unit derived from the α-olefin having 3 to 20 carbon atoms is preferably 5 mol% or more. More preferably, it is 10 mol% or more. When the content ratio of the structural unit derived from the α-olefin is within the above range, the transparency and bleeding resistance of the multilayer sheet are further improved. In particular, in consideration of the flexibility of the multilayer sheet, it is preferable to use a polymer having a content of the structural unit derived from the α-olefin of 15 mol% or more. About an upper limit, it is less than 50 mol%, Preferably it is 40 mol% or less, Most preferably, it is 30 mol% or less.

  Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and 1-undecene. , 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nanodecene, 1-eicosene and the like linear α-olefins; 3-methyl- Examples include branched α-olefins such as 1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. These can be used in combination of two types.

  Among them, the number of carbon atoms of the α-olefin is preferably 3 to 10 and more preferably 3 to 8 in terms of versatility (cost, mass productivity, or availability).

  The ethylene / α-olefin copolymer is preferably an ethylene / propylene copolymer, an ethylene / 1-butene copolymer, an ethylene / 4-methyl-1-pentene copolymer, or an ethylene / 1-hexene copolymer. These ethylene / α-olefin copolymers have a structural unit content derived from ethylene of 50 mol% or more.

In these copolymers, the proportion of the structural unit derived from α-olefin is preferably 5 mol% or more when the amount of all structural units (monomer units) constituting each copolymer is 100 mol%. More preferably, it is 10 mol% or more.
In the adhesive layer (B), the ethylene / α-olefin copolymer may be used alone or in combination of two or more.

  The ethylene / α-olefin copolymer can be produced, for example, by a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method or the like using a metallocene catalyst.

The density of the ethylene / α-olefin copolymer, measured in accordance with JIS K7112, is preferably 850 kg / m ³ or more, more preferably 860 kg / m ³ or more, and particularly preferably 870 kg / m. ^{There are 3} or more. When the density of the ethylene / α-olefin copolymer is at least the above lower limit, the heat resistance is further improved.
The density of the ethylene / α-olefin copolymer, measured in accordance with JIS K7112, is 920 kg / m ³ or less, more preferably 910 kg / m ³ or less. When the density of the ethylene / α-olefin copolymer is not more than the above upper limit value, the adhesiveness and transparency of the multilayer sheet are further improved.

  The content of the ethylene copolymer (B2) in the adhesive layer (B) is 100% by mass of the total amount of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). 50 mass% or more and 99 mass% or less are preferable, 75 mass% or more and 99 mass% or less are more preferable, 85 mass% or more and 98 mass% or less are more preferable, and 90 mass% or more and 97 mass% or less are especially preferable. When the content of the ethylene-based copolymer (B2) is within the above range, the performance balance of transparency, adhesiveness, moisture resistance, insulation, flexibility, heat resistance and workability is further improved. can do.

It is preferable that at least a part of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) in the adhesive layer (B) is graft-modified with a silane coupling agent. Thereby, the performance balance of the adhesiveness to the base material of the solar cell sealing material multilayer sheet 10 and a photovoltaic cell and workability can be made still better.
Here, graft modification of the silane coupling agent to the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) is, for example, an epoxy group-containing ethylene copolymer (B1) or an ethylene-based copolymer. Using a method of reacting the copolymer (B2) with a silane coupling agent having an amino group or an epoxy group under heating (for example, 100 ° C. to 200 ° C.) (graft modification method 1), or using a polymerization initiator And a method of graft-polymerizing a silane coupling agent having a polymerizable group to the epoxy group-containing ethylene copolymer (B1) or ethylene copolymer (B2) (graft modification method 2).
In the graft modification method 1, the amino group or epoxy group in the silane coupling agent reacts with the epoxy group or carboxyl group in the epoxy group-containing ethylene copolymer (B1) or ethylene copolymer (B2). By doing so, a silane coupling agent is grafted to the side chain of the epoxy group-containing ethylene copolymer (B1) or the ethylene copolymer (B2).
In the graft modification method 2, for example, an epoxy group-containing ethylene copolymer (B1) or ethylene copolymer (B2), a silane coupling agent having a polymerizable group, and a radical polymerization initiator are used as an extruder. Using a kneader, Banbury mixer, etc., melt-kneading at a temperature above the melting point of the epoxy group-containing ethylene copolymer (B1) or ethylene copolymer (B2) and above the decomposition temperature of the radical polymerization initiator Can be manufactured. These reactions can also be performed in a solution.

As the polymerization initiator, those usually used can be used, but organic peroxides are preferred.
As the organic peroxide, a known organic peroxide that can be used as a polymerization initiator can be used. Specifically, a diacyl peroxide compound, an alkyl peroxy ester compound, a peroxy dicarbonate compound, a peroxy carbonate can be used. Examples thereof include compounds, peroxyketal compounds, dialkyl peroxide compounds, hydroperoxide compounds, and ketone peroxide compounds.
Of these, dialkyl peroxide compounds are preferable, and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,3-di (2-t-butylperoxyisopropyl) benzene, di-t- Butyl peroxide, 2,5-dimethyl-2,5-di (t- (butylperoxy) hexyne-3 is more preferred.
The polymerization initiator is usually 0.1 to 5 parts by mass, preferably 0.5 to 3 parts per 100 parts by mass in total of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). It can be contained in an amount of parts by mass.

Examples of the silane coupling agent having a polymerizable group include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, Examples include 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltriethoxysilane.
Examples of the silane coupling agent having an amino group include N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- ( Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- Examples include phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, and the like.
As the silane coupling agent having an epoxy group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycid Examples thereof include xylpropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane.
The silane coupling agent is usually 0.01 to 5 mass, preferably 0.05 to 100 parts by mass in total of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). It can be contained in an amount of 3 parts by mass, more preferably 0.1 to 2 parts by mass.

  The epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) are both melt flow rates (JIS K7210-1999, 190 ° C., 2160 g load; hereinafter abbreviated as MFR). Is preferably in the range of 0.1 g / 10 min to 50 g / 10 min. Furthermore, it is preferably in the range of 0.5 g / 10 min to 30 g / 10 min, and particularly preferably in the range of 1 g / 10 min to 20 g / 10 min. By selecting a copolymer within this range, it becomes easier to process the sheet required as the multilayer sheet 10 for solar cell encapsulant, and a desired sheet can be obtained. Thereby, when a solar cell module is produced, the favorable adhesiveness and the suppression effect of unnecessary damaging are acquired.

  In the adhesive layer (B), the total content of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) is preferably when the entire adhesive layer (B) is 100% by mass. It is 50 mass% or more, More preferably, it is 65 mass% or more, More preferably, it is 80 mass% or more, Most preferably, it is 90 mass% or more. When the total content of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) is within the above range, transparency, adhesion, moisture resistance, insulation, flexibility, heat resistance and The performance balance of workability can be further improved.

The adhesive layer (B) can contain various additives within a range that does not impair the object of the present invention. Examples of such additives include a crosslinking agent, a crosslinking aid, a silane coupling agent, an ultraviolet absorber, a light stabilizer, and an antioxidant.
About these additives, the thing similar to what was mentioned by the resin layer (A) can be used.
Additives are used for resin modification and durability improvement.

The crosslinking aid can be used as necessary, and is usually 5 parts by mass or less, based on a total of 100 parts by mass of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). Preferably it can be made to contain in the quantity of 0.1-3 mass parts.
The silane coupling agent is usually 5 parts by mass or less, preferably 0.02 to 3 parts by mass with respect to 100 parts by mass in total of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). It can be contained in an amount of parts. When the silane coupling agent is contained in the above range, the adhesion between the multilayer sheet and the protective material or solar cell element can be further improved.
The antioxidant, light stabilizer and ultraviolet absorber are each usually 5 parts by mass or less for a total of 100 parts by mass of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2), Preferably it can be made to contain in the quantity of 0.1-3 mass parts.

In addition to the additives described above, the adhesive layer (B) can contain additives such as a colorant, a light diffusing agent, and a flame retardant as necessary.
About these additives, the thing similar to what was mentioned by the resin layer (A) can be used.

The manufacturing method of the multilayer sheet 10 for solar cell sealing materials which concerns on this embodiment can be performed by the well-known method using a multilayer T-die extruder, a multilayer inflation molding machine, etc., for example. For example, a resin composition (A) containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component, an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer and a density of Resin containing at least one ethylene copolymer (B2) selected from ethylene / α-olefin copolymers of 920 kg / m ³ or less (excluding an epoxy group-containing ethylene copolymer (B1)) The composition (B) can be obtained by supplying the composition (B) from the main extruder of the multilayer T-die extruder and the hopper of the slave extruder and performing multilayer extrusion molding into a sheet form from the tip of the T die.
Here, the various additives described above may be added to the resin composition (A) and the resin composition (B).

2. Solar Cell Module FIG. 2 is a cross-sectional view schematically showing an example of the structure of the solar cell module 1 according to the embodiment of the present invention.
The solar cell module 1 according to this embodiment includes at least a substrate 2 on which sunlight enters, a solar cell element 3, a back sheet 4, and the solar cell element 3 sealed between the substrate 2 and the back sheet 4. And the sealing resin layer 5 comprised by the multilayer sheet 10 for solar cell sealing materials which concerns on this embodiment is provided.
The solar cell module 1 according to the present embodiment can be produced by fixing the solar cell element 3 sealed with the multilayer sheet 10 for the solar cell sealing material according to the present embodiment on the substrate 2.

As such a solar cell module 1, various types can be illustrated. For example, a multilayer for solar cell encapsulant from both sides of the solar cell element 3 such as substrate 2 / multilayer sheet 10 for solar cell encapsulant / solar cell element 3 / multilayer sheet 10 for solar cell encapsulant / backsheet 4. The solar cell element 3 formed in advance on the surface of the substrate 2 such as glass or the like sandwiched between the sheets 10 is like a substrate 2 / solar cell element 3 / multilayer sheet 10 for solar cell sealing material / back sheet 4. A solar cell encapsulant multilayer sheet 10 on a solar cell element 3 formed on the inner peripheral surface of the substrate 2, for example, an amorphous solar cell element formed on a fluororesin-based sheet by sputtering or the like. And the back sheet 4 can be formed.
In the solar cell module 1, when the solar cell encapsulant multilayer sheet 10 has a three-layer structure of adhesive layer (B) / resin layer (A) / adhesive layer (B), the adhesive layer (B) as the outer layer Is laminated so that one of the two contacts the solar cell element 3 and the other outer layer, the adhesive layer (B), contacts the substrate 2 or the back sheet 4. Moreover, when the multilayer sheet 10 for solar cell sealing materials has a two-layer structure of resin layer (A) / adhesive layer (B), the resin layer (A) contacts the solar cell element 3 and the adhesive layer (B Are preferably laminated so as to contact the substrate 2 or the back sheet 4.

Examples of the solar cell element 3 include silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, III-V groups such as gallium-arsenic, copper-indium-selenium, copper-indium-gallium-selenium, and cadmium-tellurium. Various solar cell elements such as II-VI group compound semiconductor systems can be used. The solar cell sealing material multilayer sheet 10 according to the present embodiment is particularly useful for sealing an amorphous silicon solar cell element.
In the solar cell module 1, the plurality of solar cell elements 3 are electrically connected in series via the interconnector 6.

As the board | substrate 2 which comprises the solar cell module 1, the board | substrate comprised by glass, an acrylic resin, a polycarbonate, polyester, a fluorine-containing resin etc. can be illustrated.
The back sheet 4 is a single or multilayer sheet such as a metal or various thermoplastic resin films, for example, a metal such as tin, aluminum or stainless steel, an inorganic material such as glass, polyester, an inorganic vapor deposition polyester, or a fluorine-containing resin. And a single-layer or multilayer sheet of polyolefin or the like. Good adhesion to the multilayer sheet 10 for solar cell encapsulant according to the present embodiment, the substrate 2 or the backsheet 4 is shown.

Although the manufacturing method of the solar cell module 1 is not specifically limited, For example, the following method is mentioned.
First, a plurality of solar cell elements 3 electrically connected using the interconnector 6 are sandwiched between the multilayer sheets 10 for solar cell encapsulant, and the multilayer sheet 10 for solar cell encapsulant is further connected to the substrate 2 and the back sheet 4. A laminated body is produced by sandwiching between. Next, the solar cell module 1 is obtained by heating and pressurizing the laminate and bonding the members.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

  The detail of the component used for preparation of the multilayer sheet for solar cell sealing materials is as follows.

<Ethylene / unsaturated carboxylic acid copolymer or its ionomer>
EMAc1 (A): an ionomer of an ethylene / methacrylic acid copolymer (ethylene content 85 mass%, methacrylic acid content: 15 mass%, 23% zinc neutralization)
EMAc2 (A): Ionomer of ethylene / methacrylic acid copolymer (ethylene content 85% by mass, methacrylic acid content: 15% by mass, 54% magnesium neutralization)
EMAc3 (A): ionomer of ethylene / methacrylic acid / butyl acrylate copolymer (ethylene content 80%, methacrylic acid content 10%, butyl acrylate 10%, 70% zinc neutralization)

<Stabilizer master batch>
EMAc1 (A) was added with antioxidant: pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF, Irganox 1010), ultraviolet absorber: 2- (2H -Benzotriazol-2-yl) -4,6-di-tert-pentylphenol, light stabilizer: bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate in a predetermined amount of biaxial extruder Was previously melt-kneaded to obtain a stabilizer masterbatch.

<EGMAVA modified composition>
Ethylene / glycidyl methacrylate / vinyl acetate copolymer (EGMAVA, manufactured by Sumitomo Chemical Co., Ltd., Bondfast 7B, ethylene content: 83 mass%, glycidyl methacrylate content: 12 mass%, vinyl acetate content: 5 mass %, MFR (190 ° C., 2160 g load): 7 g / 10 min): 49 parts by mass, ethylene / vinyl acetate copolymer (vinyl acetate content: 19% by mass): 49 parts by mass, γ-methacryloxypropyltrimethoxy Silane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM503”): 1.5 parts by mass and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi Corp.) Product name “Lupelox 101”): 0.5 part by mass is mixed in advance, and graft polymerized with a single screw extruder at a melting temperature of 220 ° C. to produce a modified EGMAVA composition Product 1 was obtained. Here, EGMAVA grafted with γ-methacryloxypropyltrimethoxysilane in EGMAVA modified composition 1 (also referred to as EGMAVA modified product 1) is an epoxy group-containing ethylene copolymer (B1) according to this embodiment. The ethylene / vinyl acetate copolymer grafted with γ-methacryloxypropyltrimethoxysilane corresponds to the ethylene copolymer (B2) according to this embodiment.

<Ethylene copolymer (B2)>
EVA1: Ethylene / vinyl acetate copolymer (ethylene content: 90% by mass, vinyl acetate content: 10% by mass)
LDPE1: Low density polyethylene (Mitsui / DuPont Polychemical Co., Ltd., Mirason 68P, density: 918 kg / m ³ )
LDPE2: Low density polyethylene (Mitsui / DuPont Polychemical Co., Ltd., Mirason 401, density: 920 kg / m ³ )
EMA1: ethylene methyl acrylate copolymer (ethylene content: 80% by mass, methyl acrylate content: 20% by mass, MFR: 8 g / 10 min)
EEA1: Ethylene / ethyl acrylate copolymer (ethylene content: 85% by mass, ethyl acrylate content: 15% by mass, MFR: 6 g / 10 min)
EBA1: Ethylene / butyl acrylate copolymer (ethylene content: 83% by mass, butyl acrylate content: 17% by mass, MFR: 7 g / 10 min)
EC1: ethylene / α-olefin copolymer (Mitsui Chemicals, Tuffmer DF840, MFR: 3.6 g / 10 min, density: 885 kg / m ³ )
EC2: ethylene / α-olefin copolymer (Mitsui Chemicals, Tuffmer DF940, MFR: 3.6 g / 10 min, density: 893 kg / m ³ )
EC3: ethylene / α-olefin copolymer (manufactured by Prime Polymer, Evolue SP0540, MFR: 3.8 g / 10 min, density: 903 kg / m ³ )
EC4: ethylene / α-olefin copolymer (manufactured by Prime Polymer, Evolue SP2540, MFR: 3.8 g / 10 min, density: 924 kg / m ³ )

[Example 1]
EGMAVA modified composition 1: 10 parts by mass and ethylene copolymer EVA1 (B2): 90 parts by mass of a resin composition (B) (compound (B-1)) obtained by dry blending were used as outer layer 1 and outer layer 2 Using a resin composition obtained by dry blending 90 parts by mass of EMAc1 (A) and 10 parts by mass of a stabilizer masterbatch as an intermediate layer, using a two-type three-layer T-die molding machine at a resin temperature of 180 ° C. The thickness ratio was outer layer 1 / intermediate layer / outer layer 2 = 67 μm / 266 μm / 67 μm to produce a multilayer sheet having a total thickness of 400 μm (0.4 mm).

<Evaluation>
(1) Adhesive evaluation Using a vacuum heat bonding machine (NPC double vacuum tank bonding machine, LM-50 × 50S), 3.2 mm thick glass / obtained multilayer sheet / PET without corona treatment The layers were laminated in this order, and bonded together under conditions of a heating temperature of 160 ° C. and a heating time of 8 minutes. Thereafter, the bonded material was left in the atmosphere and gradually cooled by natural cooling. A slit having a width of 15 mm was formed in a sheet portion of the completed laminate to obtain a test piece, which was installed in a tensile tester. The multilayer sheet and PET were pulled apart at a tensile speed of 100 mm / min, and the maximum stress was determined as the initial adhesive strength (N / 15 mm).
Further, the laminate was stored at 85 ° C. and a humidity of 90% RH for 1000 hours, and the adhesive strength after 500 hours and the adhesive strength after 1000 hours were also determined. The obtained adhesive strength was defined as the PET adhesive strength in each laminate. The obtained results are shown in Table 2.

(2) Transparency evaluation A laminated body prepared by laminating in the order of 3.2 mm-thick glass / obtained multilayer sheet / 3.2 mm-thick glass in the same manner as the adhesive evaluation in (1), The total light transmittance (unit:%) and Haze (cloudiness, unit:%) were measured using a haze meter manufactured by Suga Test Instruments Co., Ltd. according to JIS K7136. The obtained results are shown in Table 2.

(3) Moisture permeability evaluation The moisture permeability g / (m ² · 24h) of the multilayer sheet was measured by a cup method (JIS Z0208 compliant, measurement atmosphere: 40 ° C. × 90% RH). The obtained results are shown in Table 2.

(4) Volume resistivity The volume resistivity of the multilayer sheet was measured according to JIS C2139 (2008). The obtained results are shown in Table 2.

[Examples 2-7, Comparative Examples 1-3]
A multilayer sheet was prepared in the same manner as in Example 1 except that the blends (B-2 to B-10) shown in Table 1 were used in place of the blends (B-1) of the outer layers 1 and 2, respectively. Evaluation similar to 1 was performed. The obtained results are shown in Tables 2 and 3, respectively.

[Examples 8 and 9]
A stabilizer masterbatch and an intermediate layer were prepared using EMAc2 (A) and EMAc3 (A3) instead of EMAc1 (A), respectively, and the same procedure as in Example 5 was used except that the obtained intermediate layer was used. Each multilayer sheet was produced and evaluated in the same manner as in Example 1. The obtained results are shown in Table 3, respectively.

[Comparative Example 4]
Using a single screw extruder, EVA1 was extruded into a sheet at a resin temperature of 100 ° C. to produce a resin sheet having a thickness of 400 μm (0.4 mm), and the same evaluation as in Example 1 was performed. The obtained results are shown in Table 3.

[Comparative Example 5]
A single-layer sheet was produced in the same manner as in Example 1 except that the outer layers 1 and 2 were not provided, and the same evaluation as in Example 1 was performed. The obtained results are shown in Table 3.

  The multilayer sheets of Examples 1 to 9 were excellent in the performance balance of transparency, adhesiveness, moisture resistance and insulation. On the other hand, the sheet | seat of Comparative Examples 1-5 was inferior to the performance balance of transparency, adhesiveness, moisture resistance, and insulation.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2015-191210 for which it applied on September 29, 2015, and takes in those the indications of all here.

The present invention also includes the following aspects.
1.
A solar cell comprising: a resin layer (A) containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component; and an adhesive layer (B) provided on one side or both sides of the resin layer (A). A multilayer sheet for sealing material,
The adhesive layer (B) is at least selected from a glycidyl group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 910 kg / m ³ or less. A multilayer sheet for a solar cell encapsulant, comprising a kind of ethylene copolymer (B2) (excluding the glycidyl group-containing ethylene copolymer (B1)).
2.
1. In the multilayer sheet for solar cell encapsulant described in
The multilayer sheet for solar cell sealing materials in which the said contact bonding layer (B) was provided in both surfaces of the said resin layer (A).
3.
1. Or 2. In the multilayer sheet for solar cell encapsulant described in
The multilayer sheet for solar cell sealing materials whose whole thickness is 50 micrometers or more and 2000 micrometers or less.
4).
1. To 3. In the multilayer sheet for solar cell sealing material according to any one of the above,
The multilayer sheet for solar cell sealing materials whose Haze measured based on JISK7136 is 40% or less.
5.
1. To 4. In the multilayer sheet for solar cell sealing material according to any one of the above,
The glycidyl group-containing ethylene copolymer (B1) is composed of ethylene / (meth) acrylic acid glycidyl copolymer, ethylene / (meth) acrylic acid glycidyl / vinyl acetate copolymer, and ethylene / (meth) acrylic acid glycidyl / The multilayer sheet for solar cell sealing materials containing at least 1 type selected from a (meth) acrylic acid ester copolymer.
6).
1. To 5. In the multilayer sheet for solar cell sealing material according to any one of the above,
The ethylene / polar monomer copolymer includes at least one selected from an ethylene / vinyl ester copolymer, an ethylene / unsaturated carboxylic acid ester copolymer, and an ethylene / unsaturated carboxylic acid copolymer. Multi-layer sheet for materials.
7).
1. To 6. In the multilayer sheet for solar cell sealing material according to any one of the above,
A solar cell encapsulant in which at least a part of the glycidyl group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) in the adhesive layer (B) is graft-modified with a silane coupling agent Multilayer sheet.
8).
1. To 7. In the multilayer sheet for solar cell sealing material according to any one of the above,
A multilayer sheet for a solar cell encapsulant, wherein the mass ratio of the ethylene copolymer (B2) to the glycidyl group-containing ethylene copolymer (B1) contained in the adhesive layer (B) is 1 or more and 50 or less. .
9.
1. To 8. In the multilayer sheet for solar cell sealing material according to any one of the above,
The resin layer (A) is a multilayer sheet for a solar cell encapsulant containing the ionomer of the ethylene / unsaturated carboxylic acid copolymer as a main component.
10.
1. To 9. In the multilayer sheet for solar cell sealing material according to any one of the above,
The multilayer sheet for solar cell sealing materials used in order to adhere | attach the electrically insulating resin film layer in which at least one surface is not corona-treated.
11.
1. To 10. A production method for producing a multilayer sheet for a solar cell encapsulant according to any one of the following:
Resin composition (A) containing ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component, glycidyl group-containing ethylene copolymer (B1), ethylene / polar monomer copolymer and a density of 910 kg / Resin containing at least one ethylene copolymer (B2) selected from ethylene / α-olefin copolymers of m ³ or less (excluding the glycidyl group-containing ethylene copolymer (B1)) The manufacturing method of the multilayer sheet for solar cell sealing materials including the process of carrying out multilayer extrusion molding of the composition (B).
12
A substrate on which sunlight is incident;
A solar cell element;
A backsheet,
Sealing the solar cell element between the substrate and the backsheet; To 10. A sealing resin layer constituted by the multilayer sheet for solar cell sealing material according to any one of the above,
A solar cell module comprising:

Claims (12)

A solar cell comprising: a resin layer (A) containing an ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component; and an adhesive layer (B) provided on one side or both sides of the resin layer (A). A multilayer sheet for sealing material,
The adhesive layer (B) is at least selected from an epoxy group-containing ethylene copolymer (B1), an ethylene / polar monomer copolymer, and an ethylene / α-olefin copolymer having a density of 920 kg / m ³ or less. A multilayer sheet for solar cell encapsulating material, comprising a kind of ethylene copolymer (B2) (excluding the epoxy group-containing ethylene copolymer (B1)). In the multilayer sheet for solar cell sealing materials of Claim 1,
The multilayer sheet for solar cell sealing materials in which the said contact bonding layer (B) was provided in both surfaces of the said resin layer (A). In the multilayer sheet for solar cell sealing materials of Claim 1 or 2,
The multilayer sheet for solar cell sealing materials whose whole thickness is 50 micrometers or more and 2000 micrometers or less. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 3,
The multilayer sheet for solar cell sealing materials whose Haze measured based on JISK7136 is 40% or less. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 4,
The epoxy group-containing ethylene copolymer (B1) is composed of ethylene / (meth) acrylic acid glycidyl copolymer, ethylene / (meth) acrylic acid glycidyl / vinyl acetate copolymer, and ethylene / (meth) acrylic acid glycidyl / The multilayer sheet for solar cell sealing materials containing at least 1 type selected from a (meth) acrylic acid ester copolymer. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 5,
The ethylene / polar monomer copolymer includes at least one selected from an ethylene / vinyl ester copolymer, an ethylene / unsaturated carboxylic acid ester copolymer, and an ethylene / unsaturated carboxylic acid copolymer. Multi-layer sheet for materials. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 6,
Solar cell sealing material in which at least a part of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2) in the adhesive layer (B) is graft-modified with a silane coupling agent Multilayer sheet. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 7,
The content of the ethylene copolymer (B2) contained in the adhesive layer (B) is 100 mass of the total amount of the epoxy group-containing ethylene copolymer (B1) and the ethylene copolymer (B2). %, A multilayer sheet for solar cell encapsulant that is 50 mass% or more and 99 mass% or less. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 8,
The resin layer (A) is a multilayer sheet for a solar cell encapsulant containing the ionomer of the ethylene / unsaturated carboxylic acid copolymer as a main component. In the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 9,
The multilayer sheet for solar cell sealing materials used in order to adhere | attach the electrically insulating resin film layer in which at least one surface is not corona-treated. It is a manufacturing method for manufacturing the multilayer sheet for solar cell sealing materials as described in any one of Claims 1 thru | or 10, Comprising:
Resin composition (A) containing ethylene / unsaturated carboxylic acid copolymer or its ionomer as a main component, epoxy group-containing ethylene copolymer (B1), ethylene / polar monomer copolymer and density of 920 kg / Resin composition containing at least one ethylene copolymer (B2) selected from ethylene / α-olefin copolymers of m ³ or less (excluding the epoxy group-containing ethylene copolymer (B1)) The manufacturing method of the multilayer sheet for solar cell sealing materials including the process of carrying out multilayer extrusion molding of the thing (B). A substrate on which sunlight is incident;
A solar cell element;
A backsheet,
A sealing resin layer constituted by the multilayer sheet for solar cell sealing material according to any one of claims 1 to 10 for sealing the solar cell element between the substrate and the back sheet,
A solar cell module comprising:

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